Filtration vs. flow. Hybrid EV.

[serpa4]

I have a new to me Plug-in Hybrid Toyota RAV4. Due to its larger battery compared to a standard hybrid, I can go 40 to 50 miles on pure electric. This means oil can sit for awhile when I charge daily, I may not use the ICE for a week or more.
My real concern is using its 300hp. This is both ICE and EV at the same time. Biggest issue: I can drive for 20 miles and have cold oil (well Florida is never below 45F). If I need to jump on the throttle for all 300hp, it will go from non running ICE to almost full throttle on a cold engine. There are some precautions the MFG may take, but don't know what to make this "less" of an issue.
So, I like really clean oil, 20 micron filters, but they all restrict flow. This was never an issue with my gas cars as I can warm them up and drive slowly at my discretion. Now with the Hybrid I want all the oil I can get since it's almost always a dry start and full throttle cold.
I was going to do Purolator Boss, but it's like 46um. That seems big. Amsoil and Purolator One are 20um, but flow is really restricted when cold, or hot for that matter.
What should I look at as a priority, flow..less restriction or filter ability to keep out debris. I've heard dry starts are the engine killers, but also heard contamination is the #1 engine killer. Since these engines live forever, maybe I need to focus on flow a "little more" than microns.
What do you all think?

 

[fantastic]

I have a new to me Plug-in Hybrid Toyota RAV4. Due to its larger battery compared to a standard hybrid, I can go 40 to 50 miles on pure electric. This means oil can sit for awhile when I charge daily, I may not use the ICE for a week or more.
My real concern is using its 300hp. This is both ICE and EV at the same time. Biggest issue: I can drive for 20 miles and have cold oil (well Florida is never below 45F). If I need to jump on the throttle for all 300hp, it will go from non running ICE to almost full throttle on a cold engine. There are some precautions the MFG may take, but don't know what to make this "less" of an issue.
So, I like really clean oil, 20 micron filters, but they all restrict flow. This was never an issue with my gas cars as I can warm them up and drive slowly at my discretion. Now with the Hybrid I want all the oil I can get since it's almost always a dry start and full throttle cold.
I was going to do Purolator Boss, but it's like 46um. That seems big. Amsoil and Purolator One are 20um, but flow is really restricted when cold, or hot for that matter.
What should I look at as a priority, flow..less restriction or filter ability to keep out debris. I've heard dry starts are the engine killers, but also heard contamination is the #1 engine killer. Since these engines live forever, maybe I need to focus on flow a "little more" than microns.
What do you all think?

This is your misconception. Go get your Purolator One or any of the others (Microgard Select, Carquest, STP etc) & you won't have an issue with your filters.

 

[kschachn]

I have a new to me Plug-in Hybrid Toyota RAV4. Due to its larger battery compared to a standard hybrid, I can go 40 to 50 miles on pure electric. This means oil can sit for awhile when I charge daily, I may not use the ICE for a week or more.
My real concern is using its 300hp. This is both ICE and EV at the same time. Biggest issue: I can drive for 20 miles and have cold oil (well Florida is never below 45F). If I need to jump on the throttle for all 300hp, it will go from non running ICE to almost full throttle on a cold engine. There are some precautions the MFG may take, but don't know what to make this "less" of an issue.
So, I like really clean oil, 20 micron filters, but they all restrict flow. This was never an issue with my gas cars as I can warm them up and drive slowly at my discretion. Now with the Hybrid I want all the oil I can get since it's almost always a dry start and full throttle cold.
I was going to do Purolator Boss, but it's like 46um. That seems big. Amsoil and Purolator One are 20um, but flow is really restricted when cold, or hot for that matter.
What should I look at as a priority, flow..less restriction or filter ability to keep out debris. I've heard dry starts are the engine killers, but also heard contamination is the #1 engine killer. Since these engines live forever, maybe I need to focus on flow a "little more" than microns.
What do you all think?

I think this same incorrect and rambling tome of misinformation has been posted before. That's what I think.

 

[UGASpike]

Biggest issue: I can drive for 20 miles and have cold oil (well Florida is never below 45F). If I need to jump on the throttle for all 300hp, it will go from non running ICE to almost full throttle on a cold engine. There are some precautions the MFG may take, but don't know what to make this "less" of an issue.

I would make it a point to switch drive modes when first getting into the car.

I also think that the oil system is still circulating while in EV. I don't know for sure, and this could be vehicle-specific, but my wife's car, I do hear some sort of pump running.

 

[ATex7239]

Toyota A25A has proven to be a solid engine across all configurations and platforms. Also the engine is not going to have a “dry” or “restricted” start based on anything you mentioned. I would not worry about this. Just change the oil/filter regularly and drive it as you normally would.

 

[dnewton3]

So, I like really clean oil, 20 micron filters, but they all restrict flow.

What makes you think this is of any significance? Where's your data to back up this concern? Sure; there's a dP across the media, but not anywhere enough to be a concern for your application.

This was never an issue with my gas cars as I can warm them up and drive slowly at my discretion. Now with the Hybrid I want all the oil I can get since it's almost always a dry start and full throttle cold.

This is part of the reason they spec very thin lubes; quick flow upon start.

I was going to do Purolator Boss, but it's like 46um. That seems big. Amsoil and Purolator One are 20um, but flow is really restricted when cold, or hot for that matter.
What should I look at as a priority, flow..less restriction or filter ability to keep out debris. I've heard dry starts are the engine killers, but also heard contamination is the #1 engine killer. Since these engines live forever, maybe I need to focus on flow a "little more" than microns.
What do you all think?

I think you're overthinking this.


Toyota is, IMO, the leading OEM in hybrid vehicles; they've essentially perfected the tech. I would trust that they've done it right.
Use any filter and lube that meets their specs, and climb down from the ledge ...

 

[EvoMan]

This has been discussed many times.

Thread 'The Myth of "Flow Over Efficiency"'
https://bobistheoilguy.com/forums/threads/the-myth-of-flow-over-efficiency.398959/

 

[ZeeOSix]

^^^ The link below in that thread makes it easier to compare filters. As said, the dP vs flow difference between oil filters really isn't going to matter except in some extreme use conditions like on a full blown race engine with a high flow oil put running near redline. Even at 9-10 GPM with hot oil (15 cSt in this case), most of those filters are running around 5-7 PSI of dP.

Post in thread 'The Myth of "Flow Over Efficiency"'

Aug 24, 2025

The dP vs flow data is on one graph to easier show how they compare at 5 GPM and 9 GPM.

X-axis is the filter number from the Filter Key table.
Y-axis is the dP in PSI.
Test conditions are on the graph.

Note for the PGI filter fans, the STP Ext Life (Filter No. 18) shows to have a pretty decent dP level (middle of the range), and they are rated pretty high in efficiency too (99% @ 20u).

• ZeeOSix

• 

 

[ZeeOSix]

I like really clean oil, 20 micron filters, but they all restrict flow.

You should read this thread. Read from the beginning if you want to understand how oil filters are ISO tested.

U

Post in thread 'Would you all like to see ISO 4548-12 Oil Filter Lab Testing Comparison, Efficiency & Capacity, Pressure vs Flow, Bubble Point, and Burst?'

Jun 4, 2021

I will get a video out with more details, but at the moment I cannot. I hope you all enjoy this summery of your favorite filters! You all have waited long enough and I appreciate you patients!

• UNC034

• 
• 
• 

 

[ZeeOSix]

Purolator One are 20um, but flow is really restricted when cold, or hot for that matter.

Where did this claim come from? ... the old misconception that high efficiency oil filters are "too restrictive"? Here's a dP vs flow test that Purolator did on a PureONE. It was some time ago, but I highly doubt they have changed much and are now "too restrictive". This filter didn't have a bypass valve so they could measure the dP vs flow all the way to 18 GPM.

 

[JHZR2]

Not sure about the confusion over having 300 hp. That answer is simple. Nobody needs more than 72 hp. So don’t drive like an idiot and slam the engine when you know it’s cold. If you know you’re going to load it heavily fairly soon, figure out how to get it to turn on (eg run the heat or something).

My bigger concern has usually been the abrupt stop after a long heavy load (like climbing a hill at speed). Then you get localized heat soak in some very small tolerance areas. Then it starts abruptly and comes up pretty fast again. That means to me that a robust oil is more important.

Any quality filter will be fine. Given how poorly I understand oe Toyota/honda filters remove particles (low efficiency), any decent name brand quality filter will be great.

 

[DCDG]

OE

 

[CleanSump]

I've dismantled engines that sat in the junkyard for years and they all had oil on the bearings. This old "there's no oil on the bearings and cam lobes until pressure is built" isn't reality no matter who claims it.

 

[Fair enough]

I have a new to me Plug-in Hybrid Toyota RAV4. Due to its larger battery compared to a standard hybrid, I can go 40 to 50 miles on pure electric. This means oil can sit for awhile when I charge daily, I may not use the ICE for a week or more.
My real concern is using its 300hp. This is both ICE and EV at the same time. Biggest issue: I can drive for 20 miles and have cold oil (well Florida is never below 45F). If I need to jump on the throttle for all 300hp, it will go from non running ICE to almost full throttle on a cold engine. There are some precautions the MFG may take, but don't know what to make this "less" of an issue.
So, I like really clean oil, 20 micron filters, but they all restrict flow. This was never an issue with my gas cars as I can warm them up and drive slowly at my discretion. Now with the Hybrid I want all the oil I can get since it's almost always a dry start and full throttle cold.
I was going to do Purolator Boss, but it's like 46um. That seems big. Amsoil and Purolator One are 20um, but flow is really restricted when cold, or hot for that matter.
What should I look at as a priority, flow..less restriction or filter ability to keep out debris. I've heard dry starts are the engine killers, but also heard contamination is the #1 engine killer. Since these engines live forever, maybe I need to focus on flow a "little more" than microns.
What do you all think?

It isn’t they are passing all the 20 micron particles every pass. If the media is accurately made, which isn’t talked about much, then use the worst examples, 50%@20 microns. At 3 gpm, 12 qts/ min, a 4 qt oil capacity circulates every 20 seconds.

 

[ZeeOSix]

It isn’t they are passing all the 20 micron particles every pass. If the media is accurately made, which isn’t talked about much, then use the worst examples, 50%@20 microns. At 3 gpm, 12 qts/ min, a 4 qt oil capacity circulates every 20 seconds.

Oil filters that are 50% @ 20 microns don't keep the oil as clean as a more efficient oil filter no matter how long it's ran - mainly because it will shed debris any time oil if flowing through it, and the more it's loaded the worse the shedding becomes. If an oil filter with horrible efficiency "cleaned up the oil" as time goes on because of multiple passes, then every particle count would be the same regardless of what oil filter was used ... but that's not the case.

One of the main reasons filters are low efficiency is because they shed a lot of debris they have already captured. That's why oil filter efficiency decreases as they load up - some worse than others. A high efficiency oil filter can't be a big debris shedder and still be high efficiency.

 

[CleanSump]

If the OP ever comes back he should read this:
Flow over Efficiency by @ZeeOSix

 

[JD!]

In addition, if your RAV4 is anything like my BMW 530e, engine power is extremely limited at cold start with the electric motor still doing most of the work to achieve the requested torque. It gradually transitions load from the e-motor to the engine over the span of a couple of minutes. I trust that Toyota, probably the most experienced manufacturer of hybrid cars, has had this figured out for a long time.